Process of and apparatus for distilling petroleum.



L. STEWART.

PROCESS OF AND APPARATUS FOR msmuwe PETROLEUM.

- APPLICATION FILED JULY7. 19H]. I 3,57 Patented Dec. 7, 1915.

6 SHEETS-SHEET 2 Fig.1 4

L. STEWART.

PROCESS OF AND APPARATUS FOR DISTILLING PETROLEUM.

APPLICATION FILED JULY 7. 1910.

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Patented Dec. 7,

pawl? 02772 012 L. STEWART.

PROCESS OF AND APPARATUS FOR msmuwe PETROLEUM.

APPLICATION FILED .lULY 7. 1910.

Patented Dec. 7, 1915.

6 EETSSHEET 3.

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Ly/nm Siewarz L. STEWART.

PROCESS OF AND APPARATUS FOR DISTILLING PETROLEUM.

APPLICATION FILED JULY], l9l0.

Patented Dec. 7, 1915.

6 SHEETS-SHEET 4.

L. STEWART.

PROCESS OF AND APPARATUS FOR DISTILLING PETROLEUM.

APPLICATION FILED JULY 7, i910.

Patented Dec. 7,- 1915.

3HEETS-SHEET 5.

L. STEWART.

PROCESS OF AND APPARATUS FOR DISTILLING PETROLEUM.

APFLICATON FILED JULY7, 1910.

Patented Dec. 7, 1915.

6 SHEETSSHEET 6.

UTE Ma ierivr orrren,

' LYMAN STEWART, OF LOS ANGELES, CALIFORNIA, ASSIGNOR TO "ONION OIL COMPANY OF CALIFORNIA, ,OF OLEUM, CALIFORNIA, A

CORPORATION OF CALIFORNIA.

PROCESS OF AND APPARATUS FOR DISTILLING'PETROLEUM.

Specification of Letters Patent.

Patented Dec. '2, 1915..

Application filed my 7, 1910. Serial No. 570,886.

To all whom it may concern.

Be it known that I, LYMAN STEWART, a citizen of the United States, residing at Los Angeles, in the county of Los Angeles and State of California, have invented a new and useful Process of and Apparatus for Distilling Petroleum, of which the following is a specification.

This invention relates to apparatus designed to take 01? from petroleum the several products which it contains without subjecting them to the intense heat which is necessary in the ordinary oil still that is subjected directly to the action of the fire.

This invention relates to a method of and means for taking ofi" from crude petroleum the several products which the same contains, and an object of the, invention Is to reduce the cost, time and labor heretofore required in accomplishing the work, and at the same time to cut off the various products in a superior manner with minimum attention, practically without still loss and Without liability of injury to any of the material treated.

My invention comprises a method which may be carried on automatically and whereby the distillation of oil through the me dium of steam is accomplished; and it also comprises apparatus consisting of a series of retorts placed at different levels, preferably one above another and "connections whereby the vapors are taken-off at intervals as the oil passes through the retorts,

said oil dropping by gravity from one retortto another until'it strikes the highest tem--v perature of steam that is required, and the invention further comprises utilizing the vapors from these several retorts for'heating the incoming oil, also utilizing the heat 1 of'the residuum in further heating the oil.

In carrying outthis inventiom'at one stage of the process a continuous flow of oil under pressure is maintained at successivc'stations where the heating'is successively effected; and the oil isv successively conveyed, after the heatings respectively, to vaporizing stations where the successive eilects are taken off successively, so that the heating for each effect is independent of the other heatings; and at other stages of the process the flowing ,oil is maintained in practically quiescent bodies while being heated, and the vapors from such bodies are tilled in this manne conducted oil as further effects to be condensed and stored or otherwise disposed of.

The invention is regarded as pioneer and is the result of much costly and long extended experiment and in some of its features may be carried out in various ways.

Therefore, I do not limit the invention to any one of the specific forms of construction or modes of'operation by which it may be carried out, but may employ any of the means or modes within the scope of the subjoin'ed description and claims.

The process is conductedby heating the oil and removing the vapors at intervals and preferably the heating is effected in three kinds of heaters, the highest heat being applied in retorts to portions of the oil from which vapors have previously been removed; the oil having previously received preliminary heating and having been sub' jected to intermediate alternate heatings and removals of vapors; the heating in the retorts being effected by a fluid heating 1 medium brought into heating relation with i parting with their calorie in the intermediate heating. The surplus heat from heater to" heater is applied so as to avoid heat loss.

The invention will now be described as practised with steam as the heating mediumfin the distillation of crude petroleum having an asphaltic base, but it is understood the invention may be employed in the redistillation of petroleum, distillates or tops. That is to say, the .higher constituents of the'crude petroleum, may be dis- The heat may be applied to the several oil bodies by external jackets or internal coils and said jackets or coils may be of any approved form, and the heating medium may. be heated at a single station or at a plurality of stations in a circulating system for such medium; and if desired, heat may be applied to the heating medium intermediate the oil bodies to be heated thereby:

but theoretically it is deemed advisable to circulating system and to maintain the circulation of the medium 1n the manner customary in circulating heating systems.

I displaced for convenience of The invention may be understood. by reference; to the accompanying drawings.

Figure 1 is an end elevation of an apparatus constructed in accordance with this invention and adapted for use in carrying on this method of distilling petroleum. Fig. 2 is a broken diagrammatic view of portions of the apparatus to illustrate the operation. Fig. 3 is a broken side elevation of the apparatus viewed from the left in Fig. -1, the top bf the crude oil tank being displaced and lowered to contract the view. Fig. 1 is a plan of the apparatus looking down from the right side of Fig. 1. Fig. 5 is a broken elevation in section on line indicated at 020 Figs. 1,2, 1 and 6. Some of the parts are illustration the traps being thus shown. Fig. 6 is a broken elevation partly in section at planes indicated by lines as, in Figs. 5 and 7. Fig. 7 is a broken longitudinal sectional elevation of the vapor heaters on line 00 Figs. 1, 2, 4: and 6.

In some of the views large arrows with the ordinal's of other views indicate the direction of sight for such other views. To avoid confusion of lines the drawings are not made to scale and various parts are variously arranged in the several views; and it is understood that in practice, the circulating and conducting pipes for oil, steam, vapor and the several eiiectsor products should be larger in proportion to the receptacles than is shown in some of the views. It is also understood that the relative location of parts is immaterial except that sufficient fall should be provided to cause appropriate flow.

The crude oil may be supplied from any source through the crude oil supply pipe 1,

Fig. 2, which is provided with the ordinary float valve 2 and discharges into the crude oil-supply tank 3 from which the oil is drawn through the cold oil pipe 4 and passes to the heating apparatus below. The float valve maintains the oil at a constant level in the supply tank so as to maintain a determined gravity pressure and flow in the system. Heat for conducting the distillation is supplied by a fluid heating medium from a suitable source as the furnace steam boiler 6, which are located at a sufficient distance below the apparatus to insure circulation through the system of steam and water of condensation from and to the boiler; the steam flowing from theboiler through steam pipe 7, superheater 8, superheater pipe 9, and certain elements of the apparatus hereinafter described, and the water of condensation flowing back to the boiler'through the return or condense pipe 5, Fig. 1, andin two colui'nns'comprlsmg five superposed pairs of heaters and another. Said receptacles are made of steel or wrought iron welded pipe having heads screwed or otherwise fastened on their ends, and may be of any suitable diameter and length within the judgment ofthe constructor. In the case illustrated they may be assumed to be about sixteen inches in diameter and forty feet long.

The uppermost pair of receptacles 11 and 12-, Fig. 2, may be termed the initial oil heater and final steam condenser; the receptacles 13, 14, 15 and 16 of one column may be termed the intermediate vapor cooling oil heaters; the receptacles 17, 18, 19 and 20 of the other column may be termed retorts, and the lowermost receptacle 21 may be termed the combined oil heater and residuum cooler.

A series of descendingheating coils is provided in the heat circulating system; the coils 22, 28, 2 1 and 25 being arranged respectively in the third series of receptacles 20, 19, 18 and 17 successively one above another, and like coils 26 and 27 being in receptacles 12 and 11 on a level with each other. Said coils are connected successively by the risers 22, 23, 24', 25, and 26'.

The top of the owest coil 22 receives from the pipe 9 a fluid heating medium as superheated steam which flows downward through the coil 22, parting with some of its heat and thence the medium flows upward from coil to coil and downward successively through the several coils and the descending condensate pipe 10.

condensate pipe 10 to the heater. Thus the A determined level or head of the cold crude oil to be distilled is maintained by the ball cock 2 in tank 3 above the level of the other elements of the system, and oilis conducted through the crude oil pipe 4 by gravity pressure from the crude oil tank'3 and flows into the first receptacle 11, preferably at the bottom thereof, and surrounds the heating coil 27 therein to. effect the by steam of comparatively low temperature and said steam and oil act upon each other at their lowest temperatures; the steam heating the oil initially and the oil cooling the steam finally to complete the condensation thereof; so that the waterof condensation may flow back to the boiler. The crude oil, thus warmed, flows upward through the .steam condenser and crude oil heater 11,

and thence from the top thereof at the end opposite that at which it enters, and flows thence through the warm oil pipe 28 into the heater 12 at one end of the bottom thereof and thence up through said heater 12 surrounding the steam coil 26 and receiving heat therefrom, and flows from the top of said heater 12 at the end opposite the inlet, and thence flows through the hot oil pipe 29 to the spew or relief tank 30 which is vapor tight except that it discharges vapors at its upper end through the 1st effect pipe 31 which leads through a condenser of some Well known effective form, where the vapors are condensed. The condensate from such vapors is thence conducted to a storage receptacle, not shown.

The hot oil pipe 29 discharges into the relief tank somewhat above the bottom thereof so as to allow discharge of the oil by gravity through the oil .pipe 32 which opens from the'relief tank a short distance above the bottom of-such tank in order that a body of oil may at all times remain in the relief tank for purposes of evaporation, thus giving still space from which the vapors may rise out of the hot oil as it passes through the relief tank. The 1st effect pipe 31 is elevated sufficiently above the oil su1= face in the relief tank so as to avoid discharge through the 1st effect'pipe of any product except the vapors that mayrise in the relief tank.

The hot oil from the relief tank 30 flows by gravity through the first vapor heater 7 descending pipe 32 and up through an ascending heating coil 33 in the first vapor ,heater 13 and thence through the second hot oil ascending pipe 31 to the 2nd effect tank 35, which is vapor tight like the relief tank 30, and has the 2nd effect vapor pipe 36 leading from its top to acondenser, and is connected by the third descending oil pipe 37 leading from the bottom of tank 35 to an ascending heating coil 38 in the second vapor heater 14, and thence from the coil 38 through the third hot oil pipe 39 to the 3rd effect tank 40 from the top of which opens the 3rd effect pipe 41.

From the bottom of the 3rd effect tanlr -10, Fig. 2, a descending oil pipe 42 leads to the ascending heating 'coil 43 in the third vapor heater 15 and from such coil through ascending pipe 44 to the 4th effect tank. 45,

the fourth descending oil pipe 47 which leads to the fourth ascending coil 48 in'the fourth vapor heater 16 and from such coil through the ascending pipe 4L9to the 5th effect tank 50 which is provided at the top with the 5th effect pipe 51 and at the bot tom with the fifth descending oil pipe 52 which leads to the ascending heating coil 53 in the oil heater and residuum cooler 21, and from said coil 53 through ascending oil pipe 54 to the top of the fourth retort 17. Retorts 17, 18, 19 and 20 are connected with each other in series through traps'55, 56 and 57, and the high heat retort 20 is connected with the oil heater and residuum receptacle 21 through a trap 58 so that the oil which passes into the uppermost retort 17 will iind its way by gravity to the residuum receptacle 21. Preferably the retorts are paired with the vapor heating tanks, the upper retort 17 being connected through vapor pipe 59 with the vapor heatingtank 13; the retort 18 being connected through vapor pipe 60 with the vapor heating tank 14; and the retort 19 being connected through vapor pipe 61 with the vapor heating tank 15. 6th, 7th, 8th and 9th effect pipes 63, 64, 65 and 66 lead-to a condenser 67 from the bottoms of the vapor heating tanks 13, 1%, 15 and 16, respectively. The effect pipes 31, 36, 41, 46 and 51 also lead to a condenser. In the instance shown, the same condenser accommodates all the effect pipes above enumerated. It is understood that a plurality of condensers may be preferable.

The oil inlet and outlet for each succeeding effect or relief tank are lower than those of the immediately preceding effect or relief tank and the effect or relief tanks are all so elevated as to maintain the oil under a pressure in excess of atmospheric pressure while the oil is being heated so that the emission of vapors in the effect or relief tanks 30, 35, 10, 15 and 50 will be facilitated; and furthermore, the action of the condenser'increases the evaporation in said tanks.

It is thus seen that 1 heat oil in the retorts by a heating medium supplied successively from lower to higher levels through the sev-, eral retorts to heat oil therein; that the oil bodies heated in said retorts discharge their hot vapors through the pipes 59, 60, 61 and 62, which lead from the tops of the retorts to the tops of the vapor heaters, respectively; and that the unvaporized products flowing from the effect tanks are heated successively,

heat to the oil bodies passing through the heating coils in the respective vapor heaters.

said vapors condense sufficiently to flow out through the lower pipes 63, 64, 65 and 66, re-

shown, through become condensed to tanks, and has parted with the higher spectively,

. gravity vapors forming the 1st, 2nd, 3rd, 1th

and 5th effects, is then passed through the coil 53 in the residuum receptacle 21 and thence flows into the uppermost one of the series of steam heated retorts whence it flows, by means of the several traps, through the retorts of successively increasing temperature; losing vapors and gaining heat at each retort and approaching the maximum heat as it descends until it flows from the bottom retort to the final residuum receptacle 21 where it may be drawn off through the pipe 68.

Throughout this process there is a constant elimination of vapors and conservation of heat; the fluids of lower temperature being at all times subjected to a heat emitted by fluid of a higher temperature. The temperatures employed will be those found most effective in the practice of the art and can be determined in the usual way by thermometers, not shown, inserted in appropriately located thermometer wells a.

In Fig. 5 the preferred form of heating coil is shown. The same comprises the well known return headers 69, at the ends of the tubular bodies of the retorts and heaters, respectively. Said headers being closed by heads 71 fastened by bolts 72. The traps 55, 56, 57 and 58 may be of uniform construction comprising a tubular body 7 3 provided with top and bottom heads 74:, 75, the inlet pipe 76 of the trap extending up inside the body 7 8 and the outlet 77 being at the bottom of the trap. From said'traps pressure equalizing pipes 78, 79, 80 and 81 are arranged to communicate with'the receptacle from which the product is taken into the trap.

The oil is gradually" heated in a series of bodies, first by the finally condensing steam in receptacle 11, then by the warmer steam in receptacle creasing temperatures from receptacles 17, 18, 19 and 20, and then by the hot residuum in receptacle 21;. and then the oil thus pro gressively heated is further. progressively heated by the progressively increasing heats of the steam coils 25, 24, 23 and 22; and that at the successlve stages of heating, vapors of different densities are emitted for the production of different effects or oil products of gradually increasing densities It is understoodthat the heating medium will be supplied at a regulated temperature and in regulated volume by well-known means satisfactory to the constructor such as thermostatic regulating devices wellknown in the art whereby the oil burners or other mometer wells at. Said wells will, as

12, then by the'vapors of inmeaevo I burners that supply the heat may be regulated either by the steam pressure or by the heat at some critical part or parts of the apparatus. No attempt is made to illustrate such regulating means.

The level of oil in the supply tank may be fifty feet, more or less, above the inlet to the relief tank or first efiect tank and the oil outlet from the first effect tank may be 10 feet, more or less, above the inlet to the second effect tank; and the tanks may be arranged to provide a head or fall of 10 feet, more or less, from tank to tank through the coils so that there will be a requisite flow through the pipes. These heads may be determined by the constructor, reference bethe level of ing had to the relative sizes of the pipes,

sirably placed at least one-third of the diameter of the retort, from the top thereof so as to give ample head room for the vapors; and said coils should, during a run, be always submerged in theoil, otherwise they are liable to superheat t e vapors and produce an incondensable gas, The traps between the retorts are arranged to maintain at determined levels, the oil bodies in the several retorts.

Theoreticallythe cuts through the effect pipes may be practically determined from the temperatures indicated in the theris usual, be filled with lubricating oil which is not liable to evaporate rapidly comes heated to the temperature of the vapor in the retort, so that the temperatures thereby involving loss. J

and which "be-z can be practically determined by a test ther- --phaltic cement. For the purpose of giving the same a high melting temperature the residuum may be drawn from the receptacle 21 into an oxidizing tank 82 where it is subjected to an air blast through a blower pipe 83 and from thence the treated asphaltic residuum may be'transferred through the draw-off pipe 85 to the usual cooling kettle, not shown. The air and the residuum are introduced at the bottomof the oxidizing tank, and the residuum or asphaltum is drawn off from the top of such tank.

The heated air from the oxidizing tank may be utilized advantageously to supply oxygen to the flames in the furnace and superheater. It may be possible in some instances to sufiiciently cool the residuum to allow the same to be immediately barreled without going to the cooling kettle.

Itis noted that by this process the oil under treatment in certain of the receptacles, to-wit: in the initial oil heater ll, final steam condenser 12, vapor cooling oil heaters 13, 14,15, 16 and residuum cooler 21 is constantly maintained under hydrostatic pressure and that such pressure is greater than atmospheric pressure and together with the temperatures of the oil in said receptacles expanded oil, or as gas or vapor, is propipes of comparatively small area and that the steam heat iscontrollable in the usual duced. It is also evident from the drawings that the escape of expanded fluids from the respective heaters is obstructed by way at the option of the attendant and that by allowing the level of the oil inthe supply tank 3 to lower, less pressure to force the oil through the system will be exerted and that this is controllable through valve 2.

It is thus seen that the process of distilling petroleum may be conducted theoretically with no still loss and with a minimum of heat and that with the apparatus shown the operationwill be practically automatic and continuous, thereby securing maximum economy in the distillation of the oils, and furthermore that the asplialts' Will be practically uniform in their character provided a uniform grade of oil is used throughout any particular run.

The relief and effect tanks constitute pressure relief stations at which the pressure maintained" on the oil while in the heaters .and 0011s is relieved, thus allowing certain vapors to readily pass off at eachstation.

I claim 1. The method set forth of separating oil into products of different densities which consists in heating the oil under pressure at different stations; conducting the oil from station to station; successively relieving the pressure at relief stationsbetween the heat-- ing stations; taking off vapors at the relief stations successively and immediately condensing the vapors.

2. The method set forth of separating oil into products of different densities which consists in heating the oil successively under pressure at a series of heating stations; conducting the oil under pressure from station to station; successively relieving the pressure at relief stations between theheating stations and taking off vapors at the re lief stations successively; heating at successive stations the oil from which vapors have thus been removed; taking off heavier vapors from such -oil at further successive heat ing stations; and conducting such vapors to appropriately heat the oil at the first-named is under absolute control of the operator series of heating stations, and thereby .condensing said vapors.

3. The method set forth of separating crude petroleum into products of different densities which consists in heating the oil under pressure at different stations; conducting the oil from station to station; successively relieving the pressure at relief stations between the heating stations and taking off 'vapors at the relief stations; progressively heating "at successive stations, the oil from which vapors have thus been removed; taking off vapors from such oil at further successive heating stations, conducting such vapors to appropriately heat the oil at the first heatingstations, and conducting the condensate to a condenser.

4. The method set forth of separating crude petroleumhaving an asph'altic base into products of different densities Which consists in progressively heating the oil under pressure'at difierent stations; conducting the oil from station to station; successively relieving the pressure at relief stations between theheating stations and taking off vapors at the relief stations successively; progressively heating at successive stations the oil from which vapors have thus been removed; taking off vapors from such oil at further successive heating stations, and conducting such vapors to appropriately heat the oil at the prior heating stations; the temperature at the final heating station being sufficient to produce an as V phaltic cement.

5. In the process of distilling petroleum, the methodset forth which consists in progressively heating the oil under pressure greater than atmospheric pressure in superposed receptacles by means of a "heating medium. that is vcaused to flow into heating relation with the contents of said receptacles successively from the lower to the upper re ceptacle, meanwhile causing the oil to flow through the receptacles under different pres: sures from the upper .to the lower receptacle, and separatelv removing the vapors that arise in the receptacles respectively.

6. In the process of distillingpetroleum,

the method set forth which consists in pro'' gressively heating the oil under pressure iscaused to flow greater than atmospheric pressure in superposed receptacles by means of a heating medium that is caused to flow into heating relation with the contents of said receptacles successively from the lower to the upper receptacle meanwhile causing the oil to flow through the receptacles under different pressures from the upper to the lower receptacle, and removing from the receptacles respectively vapors that arise therein and applying the hotter vapors to heat the cooler oil.

7. In the process of distilling petroleum, the method set forth which consists in progressively heating the oil under pressure greater than atmospheric pressure in super posed receptacles by means of a heating medium that is caused to flow into heating relation with the contents of said receptacles successively from the lower to the upper receptacle, meanwhile maintaining the oil in the receptacles at definite levels below the tops of the receptacles under different pressures, and causing the oil to flow through the receptacles from the upper to the lower receptacle, and removing the vapors from the receptacles respectively.

8. In the process of distilling petroleum, the method set forth which consists in progressively heating the oil under pressure greater than atmospheric pressure in superposed receptacles by means of a heating medium that into heating relation with the contents of said receptacles successively from the lower to the upper receptacle, meanwhile maintaining the oil at definite levels in the receptacles, causing the oil to flow through the receptacles under different pressures from the upper to the lower receptacle, removing from the receptacles respectively the vapors that arise therein, and applying suc'h vapors for pre-heating the oil and thereby removing lighter vapors therefrom. I

9. In the art of distilling petroleum, the method set forth which consists in heating the oil under pressure greater than atmospheric pressure by a fluid-heating medium progressively in a series of receptacles; causing the oil'and the heating medium to flow from receptacle to receptacle in reverse directions and under different pressures, and taking ofi vapors from'the oil in the receptacles, respectively.

10. In the art of distilling petroleum, the method set forth which consists in heating the oil under pressure greater than atmospheric pressure by a fluid-heating medium progressively in a series of receptacles; causing the oil and the heating medium to flow from receptacle to receptacle in reverse directions and under different pressures, taking off vapors from the oil in the receptacles, respectively, applying such vapors to heat the oil supplied to said receptacles, ing off vapors from the oil thus heated.

the vapors.

1 ent levels; means and tak-.

11. The method of distilling oil set forth which consists in heating oil-under pressure greater than atmospheric pressure in a plurality of bodies arranged at difierent levels; supplying a stream of oil to the uppermost body, conducting oil from body to body by gravity, maintaining the oil bodies at determined levels and under different pressures, maintaining confined spaces abovethe oil bodies respectively, progressively heating the oil bodies from the lowermost upwardly successively, conducting vapors from the confined spaces, and condensing said vapors.

12. In the distillation of petroleum the method set forth which consists in conducting the oil by gravity from one level to a second level through a third level which is lower than the second level; maintaining different pressures at the difierent levels, heating the oil under pressure greater than atmospheric pressure at the lowermost level and taking off vapors of the second level;

body

meanwhile avolding the introduction of aqueous vapor to the oil.

13. In the distillation of oil the method 4 second series; applying heat through a flowing heating medium, successively to the bodies in the third and first series successively, so that the heatingmedium is gradually cooled as it heats the bodies successively; removing vapors fromthe oil as it passes from body to body, conducting heat from the bodies of the third series and therewith heating the bodies of the second series,

taking off vapors from the oil between the bodies of the second series; and condensing 14. Apparatus for distilling oil compris ing a plurality of retorts arranged at different levels; means for supplying oil to the uppermost retort; means to conduct the oil from retort to retort bv gravity and to maintain bodies of oil in said retorts under pressure above atmospheric pressure at determined levels below the tops of the retorts respectively; means within the retorts and below such levels to heat the bodies of oil respectively; means to convey vapors from the tops of the retorts respectively, and means to draw olf the residue from the lowermost retort.

15. Apparatus for distilling oil comprising a plurality of retorts arranged at differuppermost retort; means to conduct the oil from retort to retort by gravity and to maintain bodies of oil in said retort under pressure above atmospheric pressure at determined levels below the tops of the retorts respectively; means within the retorts and befor supplying oil to the low such levels to heat the bodies of oil respectively; means to convey vapors from the sure above atmospheric pressure at deter.

mined levels below the tops of the retorts; means within the retorts and below such levels to heat the bodies of oil respectively;

a series of oil heaters; means to convey vapors from the tops of the retorts respectively to said heaters; means to draw off residue from the lowermost retort; means to conduct the supply of oil through said oil-heaters on its way to the uppermost retort, and means to remove vapors from the oil thus heated, after the heatings successively.

17'. Apparatus for distilling oil comprising a series of retorts, a series of vapor receptacles, a preliminary oil heating recep tacle, a supply tank, a pipe to convey oil from the supply tank to the preliminary oil heating receptacle, effect tanks, a pipe leading from the preliminary oil heating receptacle to the first eflect tank, heating coils in the vapor receptacles, respectively, pipes connecting the effect tanks successively with each other through the heatlng 0011s, a pipe connecting the last effect tank with one of the retorts, traps connecting the retorts successively, means for heating the retorts successively from the lowermost retort upward, said means being arranged to conduct the surplus heat from each lower retort to the next higher retort, means to conduct the heating medium from the highest retort to the preliminary oil heating receptacle, means to maintain a circulation of heating medium through-the retorts, and preliminary heating receptacle, and means to draw off residuum from the lowermost retort.

18. Apparatus for distilllng Oll comprismg a series of retorts, a series of vapor receptacles, a preliminary oil heating recep-- tacle, a supply tank, a pipe to convey oil from the supply tank to the preliminary oil heating receptacle, effect tanks, a pipe leading from the preliminary oil heating recep tacles to the first effect tank, heating coils in the vapor receptacles, respectively, pipes connecting the effect tanks successively with each other through said heating coils, a pipe connecting the last effect tank with one of the retorts, traps connecting the retorts successively, means for heating retorts successively from the lowermost retort upward, said means being arranged to conduct the surplus heat from one retort to the next higher retort, means to conduct the heating medium from the highest retort to the preliminary oil heating receptacle, means to maintain a circulation of heating medium through the retorts, and the prellminary the heat of the residuum to heat the oil between the last effect tank and the first retort. 19. A method of distillation comprising causing fluid to flow under a given head,

heating said fluid under a different pressure for each stage, and then drawing off the resulting vapors under a diminished pressure.

22. A method of fractional distillation comprising the vaporization of different constituents of a fluid in successive stages by heating said fluid under greater pressure than atmospheric pressure, and then drawing-off the resulting vapors at substantiallyatmospheric pressure.

In testimony whereof, I have hereunto set my hand at Los Angeles, California, this 30th day of June,'l910.

LYMAN STEWVART. In presence of- JAMES'R. TowNsEND, JOHN A. MORRIS.

heating receptacle; and means for utilizing .stituents of a fluid in successive stages by 

